1. Field of Endeavor
The present invention relates to the field of non destructive testing of test objects. It relates to a method for determining geometrical characteristics of an anomaly in a test object and to a measuring apparatus for carrying out the method.
2. Brief Description of the Related Art
Applicant is aware that the maximum of the surface plane quadrature component (out-of-phase component) of the crack-related magnetic field anomaly (By,0″(ω)) in the alternating magnetic field of a crack which extends into an electrically conducting test object from the surface of the test object, contains useful information with respect to the geometry of the crack. The advantage of such a process is that the measured magnetic field variable primarily depends on the depth of the crack rather than on the crack volume, as is the case, for example, in a static magnetic field. However, the crack depth cannot be correlated with the measured By,0″max(ω) without additionally knowing the skin depth and the magnetic permeability of the test object.